The whole track is formed by connecting the guideway girders one by one; each of those is placed across two adjacent supporting columns. For the modern high speed track-bound transportation system such as the maglev train, etc. it requires that the guideway must be of extremely high accuracy, the deformation and the deflection of the guideway due to the influence of the factors of temperature difference, dynamic load and etc. must be controlled within a very small range, when the train is in high speed running. In the case of the traditional bridges, there is no difficulty to solve the problems of deflection and the hogging back of the girders caused by the temperature difference or dynamic load, but in the case of the guideway for the running of the modern high-speed track-bound vehicle, especially for the running of the maglev train, these small deformations caused by the temperature difference or dynamic load will influence the high-speed running of the train.
Through calculation it is known that in comparison of the structural functions of a continuous girder and two simply supported girders of the same section, the former has the superiority in the control of the deformation caused by the temperature difference and the dynamic load. But the guideway with continuous girder structure generally adopts such a construction mode, i.e. the girders have to be pre-fabricated in factory and then erected on site. Because the size and the weight of the continuous girder itself are too big, and in the meantime because the multi-span continuous girder belongs to a multi-point supported external hyper-static structure, in the process of transporting, lifting and installing the multi-span continuous girder must be kept in a multi-point supporting state from the beginning to the end, as well as the dislocations of any supporting point also must be controlled within a small range in order to ensure the safety of the multi-span continuous girder itself. If not, the damages of multi-span continuous girder will occur easily in the whole process of the guideway construction. Therefore in the process of the construction not only a parallel road of high class has to be built along the guideway which is specially used for transporting the multi-span continuous girder, simultaneously the special carrier for the multi-point supported girders and the crane specially for the multi-point synchronous lifting must be available. These will bring many difficulties in fabrication, processing, transportation, installation and positioning, as a result, the cost of fabrication and construction will greatly increase.
Under the action of temperature difference, all the support reaction forces of continuous girder at intermediate column, whether along vertical direction or along horizontal direction, generally are quite greater than those of simply-supported girder. From the view point of the viaduct foundation structure, it has a better function for resisting vertical reaction force, the increase of the vertical reaction force is insensitive to the construction cost of the lower foundation, but its function for resisting horizontal reaction force always is poorer. Each time, even a small increase of the horizontal reaction force caused by the upper structure will make a great increase of the material consumption for the lower foundation. It is especially so in the case of soft soil foundation.
The German Patent DE19936756 disclosed a method to connect several simply-supported type girders to be a continuous girder as shown in FIG. 1. The method of Patent DE19936756 yet is to connect these simply-supported type girders to be an entirely continuous girder whether observing it along vertical direction or observing it along horizontal direction, namely it is connected to be a truly continuous girder. Thus, such a structural mode cannot overcome the disadvantage that in this case the horizontal support reaction force of the continuous girder at the intermediate column is too big, so it is unable to achieve the objective of decreasing the construction cost of the lower foundation.
Additionally, in Patent DE19936756 a mode of embedded guide-screws and toothed-structure is used for connecting and positioning two simply-supported girder-segments. Because the guide-screw and the toothed structure all are embedded and positioned before pouring concrete or formed during pouring concrete, even though two adjacent segments of girder are poured at the same time, yet it can only be ensured that the positions relative to the concrete structure elements between two adjacent girder-segments are aligned. But for the structure of maglev guideway line or other high-speed track-bound transportation, the accurate positioning of space position means the continuous alignment of the phase positions among all the functional surfaces of the track. Moreover, the dimensions and positions of these functional surfaces are determined by the successive machining and the accurate assembly carried out after the pre-fabrication of the concrete main body of guideway girder has been completed. In this case, the dimensions of original guideway girder structural element had been corrected by reducing or complimentarily adding material, thus the dimensions and positions of finally-finished functional surfaces of the guideway girder are far different from those of the original concrete girder-segment structural element. Hence the method of using embedded guide-screws and toothed structures of Patent DE19936756, in fact, cannot achieve the objective for accurately positioning two adjacent girder-segments.